Telephony.



M'. L. JOHNSON.

TELEPHONY. APPLICATION FILED MAY 22, 1911.

I 1,105,346. v Patented Ju1 28,1914.

M. JOHNSON. v

TELEPHONY. KP'PLIOATiON ritnn MAY 22, 1911.

Patented -.Iu1 .28, 1914.

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tb h TSQ Ma U D I: FBI I To all whom/ it may concern:

UNITED STATES. PATENT orrion.

.MORTON JOHNSON, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO FRANK B. COK COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONY.

Specification of Letters Patent.

Patented July28, 191a.

Application filed May 22, 1911. Serial No. 628,778.

Be it known that I, Mon'roN'L. J oiiNsoN, citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephony, of which the following is a full, clear, concise, and.

exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to telephone exchange systems and particularly to that class of telephone exchange systems in which telephone lines are automatically extended, and my invention is of service. in connection with those telephone exchange systems in which the selecting mechanism in any way takes part in efiecting the extensions of the telephone lines, whether such extensions are in the form of called lines or are mere link connectors limited to location at the exchange.

vision of means whereby the selecting mechanism that performsthe function or functions above mentioned may also be employed to apply ringing current to a calling party line whereby a call may be initiated at one station upon a party line and be received at an station upon the party line without the intervention of especially provided selecting mechanism such as has been hitherto employed for the sole purpose of applying ringing current to calling party lines. By means of my invention I am enabled to eliminate the especially provided selecting mechanism hitherto associated with party lines for the purpose mentioned.

The telephone line extending selecting mechanism is, in accordance with another feature of my invention, adapted selectively to connect sources of current of different character individually suited to signal receivers at the party line stations whereby any partyline station may selectively signal any other party ,line station. By this feature of my invention code signals need i not be employed, but I do not-limit my invention-to systems inwhieh code signals areabsent. I I D a Bymeans of my invention the selector switch operated by a calling party line opcrates to conve selected calling :current from the selecte source back upon the same line from which a call is being initiated whereby i'eiiert edcalls may be effected with- My invention hasfor its object the pro-' with the party line.

out employing connector switches between that selector switches and the line from I by reference to the accompanying drawings showing an embodiment thereof in the form of an automatic telephone exchange system,

"and in which drawings Figure 1 shows -a party telephone line w th four stations connected therewith, and F 1g..2 shows the automatic exchange end of said party telephone line and automaticallyoperated selecting mechanism for automatically efi'ecting the extension of the party telephone line and also for connecting a source of ringing current with the party telephone line when the called station is on the same line with a calling station.

I will first describe, somewhat in detail, the particular party line station equipment illustrated in Fig. 1, it ,being understood that I do not'limit myself,-however, to the particular equi ment shown. The telephone line extends rom the exchange 'to two limbs 1, 2 and, in the embodiment of the invention illustrated, is normally connected at its two sides with the poles of a battery 3, the side 1 being grounded and connected through the ground to the positive pole of the battery 3,-and the negative pole of the battery 3 being connected with the side 2 of the line. The current furnished by thebattery 3 is preterably uni-directional. Mechanism isprovided at the exchange for reversing the cur-- rent applied to the line after a party at one of the telephone station's upon the line takes the line for use,,the source of current 3,being itself then reversed so that theysidta l is charged from the negative pole the battery and the side 2 is charged from the :positive pole of the battery. The apparatus y which the battery 3 is reversed, and which is illustrated in Fig.2, is familiar to those that are skilled in the art of automatic telephony and will be later more fully referred to.

I have shown four party line stations A B C D though I do notlimit myself to the number of stations that, are connected As the invention is illustrated, the equipments at the fourjstations are identical except, if desired, thesignal receivers at the difi'erent-stations 'n'iay be of harmonic tvpe to respond to wave. orm current of different periodieities to be selectively impressed upon the line at the ex-- resistance.

change. The signal receivers may bealike, if desired, in which. event code signals should be employed.

Similar parts at the difierent stations will be given similar characters of reference, one station being specifically described.

In the system illustrated, being an automatic telephone exchange system, I have illustrated'a well known type of switching mechanism at each telephone station for operating the selecting mechanism at the ex-' change. y

In the embodiment of the invention illustrated, the switching mechanism is controlled by a well known dial mechanism that includes a spring winding finger ring or' dial 4. The lever 5 engaged by the-finger;

at the limit of the dial, stroke releases the spring actuated device that intermittently operatesthe circuit opening switch 6 during the return of the springactuated mechanismj to normal.

It is not necessary to describe in furtherdetail the switching mechanism that is employed to operate the selecting mechanism at; the exchange and furthermore, the invention is not to be limited to the particular type of" switching mechanism illustrated. It should be said, however, that itis usual, where dial mechanism is used, to employ a master? switch including contacts 7- -and 8, inconjunction with the switching device 6 and in? serial relation therewith, this master switchj bein controlled by the switch hook 9. The} 136161510116 receiver 10, when upon its switchhook operates to depress the element 8 of the master switch and there open the circuit through switch 6, through the intermediation of the depressing finger 11 and the right hand endportion of the lever 12 thendepressed by the finger 11, the right hand end; portion of the lever 12 being mechanically connectedjwith the switching element 8 by means of astrut, 13. The swit'chhook, when depressed causes pawl 11 to hold the dial.

'There. is a low-resistance bridge conductor at each telephone station that includes the telephone transmitter 14 having one terminal tele honically connectedwith the limb 1 of the te ephone line,- and the receiver 10 in serial relation with the transmitter 14, the dial switch 6, and the contacts 7 and 8.

The normally open connection which has just been traced between the sides of the telephone line is in parallel relation with another bridge conductor which is desirably of high resistance and is preferably normally open at the contacts 15, 16. Thissecond bridge conductor includes a magnet 17 which is preferably polarized, and the entire re-- sistance of this second bridge conductor is preferably located in the magnet which may be wound, for example, to ten thousand ohms The armature of the polarized magnet 17 is preferably held in a predetermined normal position by means of a spring 18 that normally "locks the nose or angular extension 19 of the armature beneath'the nose or angular extension 20 of the intermediately pivotedclever 12. 'A spring 21 nor mally presses the nose 20 against the nose 19.

The contact element 16 is mechanically connected with the finger 11 so that said contact 16 is permitted, to engage the contact .15 when the associated telephone receiver 10 at a calla ing station isremoved fromits hook, whereby the high resistance bridge, conductor -in cluding the magnet 17 is closed whereupon current from the battery 3 is permitted initial flow over the line sides in a direction that will-enable the. magnet 17 to'respond anddraw its armature 19 from engagement with the'nose 20 of the lever 12 against the force of the spring 18 whereupon the spring the exchange to enable such selecting mechanismto operate. The high resistance shunts that include the magnets 17 do not permit of the diversion of suliicientcurrent from the low resistance shunts to interfere with the control that the switching mechanism in 'such' a low resistance shunt at a station which has appropriated the line has overthe selecting mechanism at the exchange.

It is of course understood that the electromagnet 17 'is responsive onlyto the current that is initially impressed upon the line owing, to the normal connection of the battery 3 with said line, this magnet atother times maintaining the telephone bridge open.

By mechanism which is well understood,

and which -will later be mentioned more Y fully, the battery 3 has its connections with the sides of the telephone line reversed so that the current impressed upon the line immediately after the line is taken for use is such that'the magnets 17 will not respond thereto, whereby these stations upon the line that are late in seeking to take the line for use cannot appropriate the line owing to the fact that the lever 12 at any station later'to seek appropriation of the line is locked by the armature of the magnet at such station, whereby the contacts 7 and 8 of the master switch cannot be engaged to close the'gap in the low resistance bridge at this later station, which-closure is essential to enable a through station to take a line for use, pawl 11 then looking the'dial. While current at any station at any time may be permitted to flow the magnet 17 at such station, yet such magnet will not respond if the battery 3-has been reversed since the magnetwill then be, so energized as merely to tend to move its armature in the same direction in which such armature is pulled by the s ring 18 without efl'ecting readjustment oi the parts that enter into the control of the r ceiver circuit and the control of the switching mechanism that governs the operation of the selecting mechanism. I therefore speak of the magnet 17 as being unresponsive to current that is caused to flow over the telephone-line in a direction opposite to the normal flow of the current. The signal receiver 22 responds to wave form current that is preferably an alternating current and is operated in a manner which is Well understood. I

I have described the operation of the equipment .at a-single telephone station in detail under the assumption that such a station is a calling station, and under such assumption the battery 3 is immediately reversed after the line has been taken for use.

When any of the stations upon the line is a called station, the battery 3 should have its normal connection with, the telephone line preserved, at least until the called station has responded in order that the magnet 17 at the called station may respond to permit the closure of the contacts 7 and 8 thereat and thereby enable the inclusion of the telephone equipment at the called station in bridge of the telephone line.

Referring now more particularly to Fig 2, the battery 3 has its negative pole normally connected with the side 2 of the telephone line through an energizing winding 23, the switch spring 24 and the normal contzict of such spring. The positive pole of the battery 3 is connected with the side 1 of the telephone line through ground and the switch spring '25 and its normal contact. When the telephone line is taken for use by va calling party at one of the stations, circuit for the battery 3 is closed at the contacts 15, '16 at that telephone station whereupon magnet 17 at such stations'isvoperated with results which'have been described. Later, the contacts 7 and 8 atv the line appropriating station are engaged to close the low resistance shunt at such appropriating station, whereupon current from'the battery 3 is increased sufficiently to energize the Winding 23 (this winding not having been previously operatively energized owing to the presence of the high resistance magnet 17 in circuit therewith) to cause the armature 26 to be attracted. The armature 26, in being attracted, pushes the contact 27 into engagement with the normal contact of the switch spring 25, thereby to bring'the energizing winding 28 intoa closed local circuit that may be traced from the grounded normal contact of the switch spring 25 through the winding 28 to the grounded battery 3 by the path marked open main bat. when the master switch is at rest, whereby the armatures 29 and 30 are attracted with the result that the battery 3 has its connections with the sides of the telephone line reversed, these connections being then traceable from the side 1 of the telephone line, thecontacts 31 that are closed by the armature 30, a winding "of magnet 36, to the negative side of the battery3 illustrated at the right of Fig. 2 '(the illustration of the battery 3 being repeated seven times for sake of clearness) thence to the positivepole of the battery which is connected with the side 2 of the telephone line through the contacts 32 closedby the armature 30. The battery stantly upon the closure of the contacts 7 and 8 at a calling station with the results which have been described. This association of the battery and telephone line is preserved during the tinge thereceiver at the calling station is free of its hook, assuming the called station to be upon another line, owing to the establishment of a locking circuit through the locking winding 33. This lock ing circuit .may be traced from the contacts 34 (closed as a consequence of the operation of the armature 35 of 'the magnet 36 included in the circuit of the battery 3 last traced, the subsequent energization of the magnet 37 controlling the contacts 34) through the contacts 38 closed by the armature 30, looking winding 33, the battery 3 and the ground that connects the battery with the contacts 34 The equipment thus far described contains novel characteristics forming the subject matter of my co-pending application Serial No. 628,777, filed May 22, 1911, but it is to be understood that while I prefer the equipment just described, I do not limit myself thereto.

Having thus somewhat fully described a telephone exchange system in connection with which my invention may be practised, I will now specifically describe the characteristics of my invention as they are preferablv embodied. Each party line station low resistance bridge conductor includes a a resistance 40, which may be of three thousand ohms, in what was previously the low resistance bridge conductor, for the purpose of sufliciently reducing the current flow therethrough and. as a consequence causing the inclusion of ringing current in circuit with the partv line to enable one station anon such line to call another station as will later appear.

Referring now more particularly to Fig.

3 is thus reversed in- [III key 39' adapted when depressed to introduce 1 2, I have employed the first selector, indicated at the middle of the figure, for en-.

abling the application of calling current the line extending selecting mechanism for ncluding the calling party line in circuit relation with a source of current, nor do 1 .limit myself to the transfer of ringing current over the talking sides of the party line.

The selector shown in Fig. 2 is, of a typehich is well knownby those skilled in the art. and is a form of mechanism that is installed by the Automatic Electric Company.

,As'is well known, this selector has wipers which swing in horizontal planes and which are vertically adjustable so asto move in different levels, bank or waiting contacts being located in these levels which are connected with conductors that extend to connectors directly or through theintermediation of other selectors, whereby called lines are automatically connected with calling lines. The wipers of the selector shown in Fig. 2 are marked 41, 42 and .43 and these wipers are caused to swing .in the selected level to suit the connection that they are to .efiect. One or more of the levels in which these wipers move includes bankcontacts that are associated with sources of current.

In the embodiment of. the invention illustrated code signaling is not employed, the

v signal receivers at the party line stationsbeing responsive to currents of diflerent character. For example, the signal receiver 22 at station A may respond to alternating current of sixteen cycles,-the signalreceiver at stat-ion B may respond to alternating current of thirty-three cycles, the signal receiver at station Gmay respond to alternating current of fifty cycles, and the signal re-' ceiver atstation D may respond to alternating currentof sixty-six cycles. If the in ention is thus to be embodied, that is if the.

signal receivers .are to be responsive to currents of di'iierent character, then there should be a plurality of levels of waiting or bank contacts associated with sources of ringing current of. different character, the

contacts in each of these levels being sepa-.'

ratelyfconnected with a plurality of generators producing current of similar character so that some generator producing current of desired character may be available to enable a calling party line station to signal another station upon the same line. In Fig. 2 I have illustrated butone set of waiting contacts 41 42 and 43 in one level, a single set of waiting contacts 41 42 and 4-3 in the 'next level, a single group of contacts 41 ,42 and 43 in thenext level, and a single group of contacts 41*, 42 and 43 in the next level. I have shown but one generator 44 in connection with the level" containing the contacts 41 42 and43 it being understood that other groups ofwaiting contacts in this level are similarly associated iwith similar generators 44. I have not illustrat'edany equipment in associationwith the bank contacts of the remaining levels, it being understood, in the embodiment of the invention illustrated, that the'generators associated with thefirst-level produce alternating current of sixteencycles, the generators associated with the contacts of the next levelproducing al ternating current of thirty-three cycles, the. generators associated with the contacts of the next/level producing alternating. current of fifty cycles, andthe generators associated with the contacts of the next level producing alternatin current of sixty-six cycles.

The calling party line, party'may select the level containing the waiting contacts that are associated with the calling generators producing current ofthe frequency or other character suited to the operation of the signal receiver 22'at the station upon the party line that is to be called, Having caused the wipers4l, 42and43 to occupy the desired level,'-these,wipers are stepped around until .waiting'contacts associated with an'unemployed generator 44 are encountered, the echanism and circuits by which idle waiting contacts are engaged and busy waiting contacts are passed ,over being so well known as not to require explanation. It is assumed, for example, that any of the sta' tions 13, C,D is aacalling party line station and 'thatstation A is theparty line station upon the same line to be called. The calling station, in such case, selects the level containing the bank contacts 41 42 and 43 and it is" assumed that these contacts which are illustrated in Fig. 2 were-previously free for selectioniand are engaged by thewipers 41, 42 and 43 for the purpose of associating the generator 44, previously unemployed, with the party line. The wipers stopping upon hese waiting contacts cause the establishment of a circuit through the relays 45 and 46 and the reinclusion of thebattery 3 in its normal-circuit relation with the party line in whichthe side 1 is connected with the positive pole of the battery and the side 2 is connected with the negative pole of the bat tery in order to enable the party at the called party line station to bring his telephone into circuit relation with the party line,

The source of'ringing current 44 has terminals in-the form of the alternate contacts of armature switches of the r nging magnet 47 whose circuit includes a switch 48 periodicallv closed and opened by amevolving cam 49. The circuit of the ringing magnet 47 also includes a switch 50 that is closed thrmigh the agency of the armatureswitch of the relav 46 and the magnet 51 in direct assoc ation with the switch 50. The switch 50 is maintained closed during the time the adjusted for this purpose.

telephone bridge at the calling party line station is closed whether such bridge includes the resistance 40 or does not include such resistance, the relay 46 being suitably The relay 45, however, is adjusted to drop its armature when the resistance 40 at a calling party-line station is included in the telephone bridge, whereby the circuit previously established through the relay 52 is opened and the switch 53 controlled by the relay 52 is closed. The switch 58 is thus adapted to be operated by the manipulation of the key 39at a calling party line station to close the circuit of the ringing magnet 47 at one point, the point 53, as often as the calling party desires. The cam 49 operates to open and close the circuit of the ringing magnet 47 at the point 48 so that during the time the key 39 at the calling station is depressed the circuit of the magnet 47 is intermittently opened and closed, whereby the selected calling generator 44 is intermittentlyincluded in circuit with and excluded from the circuit of the party line.

During the time that the generator is upon the line, the armature switches of the magnet 47 are removed from their normal contacts so that the circuit of the relay 46 is then open. The switch 50 is maintained closed, however, owing to the establishment of an alternate circuit for the relay 51 which may be traced from the grounded battery 3 through the winding of the relay 51 to the uppermostarmature switch of the magnet 47 and the grounded contact then engaged by said uppermost armati'nre switch.- As the invention is illustrated, the called party can-, not secure telephonic connection with the" party line until the battery 3 is again included in its normal circuit relation with the line, which condition occurs when the circuit through the ringing magnet 47 is opened at 48. I, however, do not limit myself to this characteristic which is sin ply preferred for engineering reasons. Wl en the called party responds, a low resistance bridge established across the sides of the party line through the telephone at the called party line station, whereby the magnet 45 is energized and the magnet 52 is consequently energized in order to open the circuit of the ringing magnet 47 at 53 during the presence of the low resistance shunt across the line at the called station or at the calling station under the assumption that the calling party has released his key 39'. Thus the generator 44. is removed from circuit relation with the line after the called party has responded or the calling party has excluded the resistance 40 from hisitelephoue bridge.

In passing it should be stated, in connection with the cmbodii ent of the invention illustrated, that the calling party keeps his key 39 depressed during the interval in which he expects the called party to respond in or der that the telephone bridge at the calling station may include the resistance 40 for the purpose of enabling sufficient current to pass through the magnet 17 at the called station. 'VVhen the relay 46 is energized, circuit is closed through the magnet 54 by way of the grounded armature switch of the relay 46 I and the contact of such switch then engaged, the winding of the relay 54 to the grounded battery 3. 'When the ringing current is applied to the party line circuit for the relay 54 is closed through the uppermost armature switch of the magnet 47, the winding of the relay 54 and the'grounded battery 3; The

armature of relay 54 is thus constantly attracted so as to place a guarding potential or condition upon the contact 41% to prevent another calling line station from appropriatwithout departing from thespiritof my invention.

Having thus described nay-invention, I claim as new and desire to secure by Letters Patent the following 1. A telephone exchange system including a party telephone line connecting a plurality of party telephone line stations with an exchange, said telephone stat-ions having signal receivers responsive to currents of differing character; selecting mechanism at the exchange and operable by the equipment at any of said party telephone line stations, when calling, for extending said party tele phone line intoconnection with other telephone lines; a plurality of sources of signaling current for supplying the signal receivers at the aforesaid telephone stations with current to which said signal receivers are responsive; and means governed at any of said telephone stations, when calling, for causing said selecting mechanism selectively to connect that one of said sources of signaling current with said party telephone line which corresponds to the station upon said party telephone line that is to be signaled by the calling station upon the same line, said selecting mechanism serving to convey signaling current from the selected source to the selected party line station.

2. A telephone exchange system including .a party telephone line'connecting a plural-v ity of party telephone line stations with an exchange, said telephone stations having sigml receivers responsive to currents ofdiffering character; selectingmechanism at the exchen' e and operable by the equipment at any 0' said party telephone line stations, when calling; a pluralit V of sources of signaling current for supp ying the signal receivers at the aforesaid telephone stations with currentto which said signal receivers are responsive; and means governed at any of said telephone stations, when calling, for causlng said selecting mechanism selectively to connect that one of said sources of signal-- ing' current with said party telephone line MORTON L. JOHNSON. Witnesses:

MARGARET D. R0153, G. L. CRAGG.

Qegiee of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

